Process for the operation of retorts and chamber ovens



29, 1936. F. BREITBACH PROCESS FOR THE OPERATION OF RETORTS AND CHAMBEROVENS Fil ed Jan. 5, 1954 rammed- Dec. 29, 1936- 4 PROCESS FOR THEOPERATION OF 'BE- TORTS AND CHAMBER OVENS Fritz Breitbach,Recklinghausen, Germany, assignor to Carl Still Gesellschatt mitbcsch'rinkter Haftnng, Recklinghausen, Germany Application January 3,1934, Serial No. 705,161 In Germany January 12, 1933 2 Claims.

In the known processes of drawing off the dis-- tillation products ofexternally heated retorts and chamber ovens in which the distillationproducts produced inside and outside the mass of fuel are drawn oiIseparately by means of detachable outlet tubes which project into theinterior of the mass of fuel, or in a known form of construction thusforming in a gas-tight connection with hollow ducts formed in the fuelmass, all the inner gases produced can only be completcly removed to thecollecting main for the inner gas in the case of coals forming tar seamswhich are difficult to pass gas through, when high negative pressures orvacua, which in pn ac tice are not very desirable, are used. The processof coking such coal by the use of the known internal suction devices iscarried out insuch a manner that in each particular case only theproportion of the entire quantity of gas which can be collected with adefinite maximum vacuum is carried off to the collecting main for theinner gases and the rest is carried ofi through the usual ascending pipefrom the gas collecting space into the collecting main for the outer gaswhich is under a slight vacuum.

The removal of the inner and outer gases together to the collecting mainfor the inner gas which is under high vacuum has not hitherto beenproposed as advantageous because it was assumed that the outer gases-asin the case of the usual high-temperature coking processwere in eachstage of the coking, inferior to the inner gases particularly inrespectof the lightoil content and the composition of the light oils andfor this reason the quality of the inner gas or of the light oils andtars would be impaired if the two were mixed.

Experiments carried out with coke oven batteries provided with the'knowninternal suction devices have, strange to say, shown that by the use ofinternal suction the composition of the outer gases during the firstpart of the coking is afiected in such a manner that the quality of thelight oil vapour and tar vapour contained therein is very similar tothat in the inner gases and vapours. The duration of this first periodof operation, when employing internal suction, during which the lightoils and tars of the outer gases agree with the light oils and tars ofthe inner gases in respect of their specific gravity, amounts, forinstance (with a carbonizing period of 34 hours and a coal with 23 percent. volatile constituents at 11 per cent. water content) to about 4hours. It-probably depends essentially upon the time required by theoven, after charging with fresh coking-coal, to completely reheat thewalls and .particularly the arch of the chamher, as the heat in themasonry is at first considerably withdrawn by charging with the coal. Itis also well known that the water content of the coking coal or of theouter gases which pass oil through the gas collecting space (or chamber)in consequence of the low concentration of the light oils or the tarvapours in the mixture of gas and steam, plays an important part in theprotection of the gases and oils from pyrogenic decomposition.

Apparatus suitable for carrying out the process disclosed herein isillustrated in the accompanying drawing wherein the figure shown is avertical longitudinal section through the center of a coke oven chamber,showing only a portion of the length and height of the chamber, and withthe novel means for carrying off the gases of distillation.

Now the process according to the present invention consists in thatduring the first hours of coking all gases are carried off to thecollecting.

main 1 for the inner gas, the outer gases being also sucked from the gascollecting space 4 without the interposition of suction tubes 3 to thecollecting main 1 for the inner gas which is under partial vacuum. Withthis object in view, one or more of the gas suction tubes 3 which aredistributed over the length of the chamber and which bridge the gascollecting space 4, are not inserted in the fuel mass I, so that the gasremoval ways 5 and 6 in the roof of the oven provide a direct connectionbetween the gas collecting space 4 and the collecting main 1 for theinner gas, in which there arebuiltregulating and closing devices [2which in accordance with the pressure prevailing in the gas collectingspace regulate the automatic removal of the outer gases from the gascollecting space or chamber to the collecting main 1 for the inner gaswhich is.

According to a further feature of the process according to theinvention, after the conclusion of the above described first operativestage of coking, the removal of the outer and inner gases oocursseparately, 1. e. the suction tubes I conduct the gas from the interiorof the fuel mass I through the known gas collecting pipes I and I to thecollecting main 1 for the inner gas, and the previously performed directremoval from the gas collecting space to the collecting main for theinner gas ceases, but in its place the connection I to the collectingmain 9 for the outer gas is established by the ascending pipe valvebeing opened. In this second coking stage-as experiments have shownthelight oils (benzine, benzene) and tars begin to be distributed to theouter and inner gas very differently as regards their amount andspecific gravity, so that the carrying out of the withdrawal of thegases from the interior of the fuel and the gas collecting spaceseparately is advantageous.

This second operative stage of the coking period hereinbefore referredto by way of an example embraces approximately the 4th22nd hour ofcarbonizing. At the end of the 22nd hour of carbonizing of generallyafter about twothirds of the carbonizing period, the tar seams in themiddle of the oven chamber begin to close together-this may even occurwith certain kinds of coal and at high coking speed after half thecarbonizing time has elapsed. At this moment the gas suction tubes forthe internal products are removed from the fuel mass or their gas-tightconnection with the hollow channels in the fuel mass is broken and thecollecting main for the inner gas disconnected from the respective oven.

Ithas been found that during the coking of the tar seam when usinginternal suction by premature condensation of tar vapours, the tar inthe tar seam becomes enriched and the quality of the gases after themoment of withdrawal of the suction tubes rises temporarily until thetar seam or the tar which has accumulated in the hollow spaces of thefuel mass is evaporated or coked. In order that these valuable gases andvapours themselves may be again collected, according to a further stepin the invention, at the end of the second operative stage of the cokingperiod already referred to, the separate removal of inner and outer gasis interrupted and all sucbeing transferred in its full strength to thegas collecting space of the oven chamber.

Example.-In coking a coal having 23 per cent. volatile constituents and11 per cent. water content within 34 hours, the sucked interior gasesduring the first three hours contained a light oil of specific gravity0.74 at 20 and a tar of 0.88 at 20 of which 3l per cent. was distilledover at 180 C. From the 4th to the 12th hour of carbonizing the innergases were carried on separately from the outer gases, the specificgravity of the light oil in the inner'gas remaining almost unchanged at0.75 at 20, while that of the light oil in the outer gas rose to 0.87 at20. The corresponding specific gravity in the case of the inner taramounted to 0.92 and the outer tar to more than 1.1. Continuing separateremoval up to the 22nd hour of carbonizing the specific gravities forbenzene and tar in the outer gas remained the same, but those for theinner gas rose to 0.81 for benzlne-benzene and 0.99 or slightly over 1.0for inner tar.

Of the operative stages described, the third may, of course, be omittedand instead after the withdrawal of the suction tubes from the inte riorof the fuel, all the gases be drawn oil as outer gases by the collectingmain under partial vacuum.

What I claim is:

1. In the destructive distillation of a body of coal over a period ofhours in a retort, the process comprising separately withdrawing to acommon gas collecting main the gases of destructive distillation evolvedfrom the interior of a body of coal and from the exterior thereof duringthe first hours of distillation, and thereafter independentlywithdrawing the interior and exterior gases evolved from said body ofcoal at a later stage to separate gas collecting mains.

2. In the destructive distillation of albody of coal over a period ofhours in a retort, the process of independently withdrawing during thelater stages of distillation the gases of destructive distillationevolved from the interior of said body of coal and from the exteriorthereof to separate gas collecting mains, and this after previouswithdrawal of gases evolved from the interior and exterior of the bodyof coal during the first hours of distillation to the collecting mainfor the gases evolved from the interior of the body of coal.

FRITZ BREITBACH.

